Inclusion of fluorine compounds in faujasite II. Heats of sorption

Abstract

Heats of inclusion in faujasite have been evaluated for CF 4 , C 2 F 6 , C 3 F 8 , n -C 4 F 10 , SF 6 , C 2 F 4 Cl 2 , and perfluorodimethyl cyclo hexane. In the case of CF 4 , C 2 F 6 , C 3 F 8 and SF 6 the degree of filling, θ, of the intracrystalline volume was in the range 0.05 to 0.9; for the more condensable molecules this range was more restricted. The sorbate-lattice interaction appears to be independent of the amount included, at least over a considerable range in θ, and is dominated by dispersion and repulsion energy contributions. As the amount of included material increases this interaction is augmented by a self-potential between sorbate molecules, the magnitude of which can be given a reasonable physical explanation. The maximum values of ─ ∆ H , where ∆ H is the inclusion heat, are several times larger than the latent heat of condensation of the liquids. Much of this difference arises from the different mechanisms of vaporization from the permanent, honeycomb structure of the crystals and from a liquid, respectively. Over the narrow range in θ where extracrystalline capillary condensation begins to replace intracrystalline sorption the heats of uptake depend on temperature. Heats of inclusion of fluoro-carbons are appreciably higher than those of corresponding hydrocarbons.